As disclosed in, for example, Japanese Patent No. 4100168, a known non-contact power feeding apparatus is configured so that a plurality of power supply devices that supply currents with synchronized current phases are connected in series to a feeder, and during power feeding, a power supply device is turned on in the feeder depending on the number of carriages to which power is to be supplied so that power can be supplied depending on the number of carriages.
The non-contact power feeding apparatus is configured so that a short-circuit unit causes a short-circuit between a current device and the feeder without stopping the entire power feeding apparatus, and thus only any one of the power supply devices can be stopped (separated) during power feeding, thereby allowing maintenance of the power supply device during operation.
However, the configuration of the known non-contact power feeding apparatus described above has the following problems:    (1) When the number of carriages exceeds an allowable number, a new power supply device is turned on, and power consumption of carriages changes in real time depending on changes in load (rotation number of a drive motor or the like) on the carriages. Thus, only with control of the number of carriages, power supply devices more than necessary may be turned on in the feeder, which may cause waste of power.    (2) On a side of the carriage, power is consumed irrespective of a state of the power supply device. Thus, when a problem occurs in the power supply device, the carriage may immediately run out of power.    (3) During supply of power from the other power supply device to the feeder, the short-circuit unit causes a short-circuit between a stopping power supply device and the feeder, and thereby the power supply device and the feeder are electrically separated, but connection between the stopping power supply device and the feeder is mechanically maintained. Thus, it is difficult to maintain the stopping power supply device at ease.